The thing that bothered me the most about the base springs was the ride variance. My 18 ltd had 20s not the 18s, so it probably lost a bit of softness compared to the xlt. In regards to ride variance, everyday, the ride would feel different. When the ride was good, to this day one of the best rides in an suv (rn the escalade where's this title, but I haven't driven the new x7 or gls), however, on it's worst days, it was one of the worst rides in a modern suv.
The variance is evident in my nav, but nowhere near as bad. Also, I def understand the Bob and weave, but I personally like that over harder bump impacts and occassional choppy rear end. The base suspension is way better in the city though. My nav is terrible in downtown. The expy was really good in cityscapes.